Millions of Americans (adults and children), including stroke victims and accidents due to traumatic brain injury (TBI) have lost the ability to open a partially paralyzed, clenched fist. Inability to open the hand precludes functional use of that hand and limits the functional use of the limb. Annually, in the US alone, a significant number of stroke survivors, estimated to be over a million, retain their ability to grasp with a varying degree of grip strength due in part to disuse brought about by the stroke. These individuals lack the ability to re-open their affected hand volitionally in order to release or accommodate objects. Many of these individuals, due to the nature of how a stroke affects the limbs, still are able to effectively control the shoulder and elbow. Consequently, the isolated loss of adequate finger motion imparts significant disability to stroke victims who otherwise should be able to functionally use their impaired upper extremity.
Most products currently available are bulky and difficult to use. Similarly, many devices are designed as therapeutic aides to permit exercising the fingers with the goal of recovery from an injury or act as a splint. In some cases, these devices measure the forces and motions of each finger providing valuable therapeutic information. These devices, in general, are not intended to assist the user in opening or closing the hand for the purpose of regaining utility of the limb.
Existing assistive devices use intrusive metal cables or employ awkward, oversized, exoskeleton housings for each finger and in some cases use small but heavy motors. Most of these devices have been designed to provide passive stretching of the fingers over a long period of time, although some, despite their bulky size, can be used to facilitate functional use of the hand in individuals who retain some grasp ability but lack hand-extension. In one such design, the suspension cable (suspension bridge-like) passive-opening device can only be worn at night to stretch the ligaments and must be worn in a fixed position to permit the fingers to stretch. Many prior art designs employ complex mechanical structures that are both difficult to manufacture, use, clean, or adjust, and are failure prone. Considering that no two hands are alike, rigid mechanical structures employing tensioning cables and supporting scaffolds are difficult, if not painful, to adjust and readjust to fit the hand.
Accordingly, there is a need in the art for a simple, convenient, mechanically robust movement device to allow opening and/or closing the fingers of hands of stroke victims and others who have lost all or part of the ability to move their fingers.